Magneto cord-circuit with secret service.



.R. I. UTTER & H. P. SCHMIDT.

MAGNETO CORD CIRCUIT W ITH SECRET SERVICE.

APPLICATION FILED JULY 26,1913- Patented J 11116 29 @Fltllt.

RICHARD I. UTTER AND HERMAN P. SCHMIDT, OF CHICAGO, ILLINOIS, ASSIGNORS TO- SWITCHBOARD .AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORP umATION' O]? ILLINOIS.

MAGNETO CORD-CIRCUIT WITH SECRET SERVICE.

mascot.

-Specification of Letter" Patent.

Patented June 29, 1915.

To all whom it may concern: I

Be it known that we, RICHARD I. Umu

and HERMAN P. SCHMIDT, citizens of the United States of America, residing in Chisrcago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Magneto Cord-Circuits with Secret Service, of which the following is a specification. 1

Our invention relates in general to secret service operators link or cord circuits for telephone systems and is directed more particularly to systems of this character in which the association of the operators telephone with, the connecting circuit is controlled by means of plug switches.

An object of our invention is to produce a system of the character described which is simple of construction, cheap to manufacture and easy to install. In the accompanying drawing we have illustrated two operators cord circuits B and C, the circuit B having its operators telephone entirely controlled by plug switches while the operators cord circuit C has its telephone circuit controlled by a manual key and a plug switch.

Referring now more particularly to the system illustrated, we have shown two magneto telephone lines A and A havin wellknown forms of substations D and l and line.circuits E and E respectively.

The cord circuit B is' an ordinary double supervisory magneto cord circuit having an answering plug F and calling plug G, said plugs being connected by talkingconductors 1 and 2. Supervisory drops 3 and 4 are bridged across the answering and call;- ing ends respectively of. the cord circuit and ringing keys J and H are also provided. An operators telephone set K is also provided being connected in bridge of the cord circuit throu h normally open contacts of answering p ugswitch L and normally generator thereat is operated tothrow the associated drop in a well-known manner vghe reby theoperator inserts an answering P ug F into the jack of line A. As the plug F is moved from its seat, the answering mg plug G from its seat whereby plug-switch L is operated to automatically connect the operators telephone set Kiacross the talking conductois of the cord. The operator now ascertains the number of the want ed subscriber and removes the associated callthe calling plug-switch M is operated to automatically disconnect the operators circuit K. The plug G is now inserted into the jack of the line A and the ringing key J operated to ring thecall bell of substation D in a -wellknown manner. The called subscriber now removes his receiver in response to the call and the two substations D and D are connected in a conversational circuit, traced over the heavily marked talking conductors. It will be noted that as lon as the plugs F and G are connected to tie calling and called substations ahd said plugs are out of their seats, the operators circuit K is dis associated from the cord circuit B, and she cannot listen in on an existing conversational circuit. Also by the use of the plug switches L and M, the connecting and disconnecting of the operators circuit K is entirely automatic and accomplished without the use of electromagnetic relays or extra manual operations.

(."mvl'ci-rcuz't r-The cord circuit C is similar to cord circuit B, the like parts he iug indicated by like reference characters with the addition of the sufiix prime. In the embodiment of y invention as illustrated in the cord ci cuit C, the operators circuit K is normally disassociated from the corresponding cord circuit C through normally opencontacts of a listening key LK. Thus, when the cord circuit C is used for interconnecting telephone lines, the re moval of the answering plug F from its seat does not affect the operators circuit K but the operator now throws the listening key LK to connect the circuit K to the cord C and upon lifting the calling plug G? from its seat, the calling interrupts its contacts so that the operators telephone K is automatically disconnected and whereby any subsequent operation of the listening key LK, does not connect the telephone K with the cord circuit. In this way the ordinary manual method of listening is provided but after a connection has plug-switch M for the operator to listen in on an existing conversation.

In embodying our invention in a telephone system, we have chosen to use ordinary magneto operators cord circuits simply for the purpose of illustration but we contemplate applying our inventioninoth'er ways than that shown and therefore we do not desire to be limited to the embodiment shown but aim; to cover all that which comes within the spirit and scope of the appended claim.

What we claim as new and desire to secure by United States Letters Patent is:

A secret service telephone s stem com prising telephone lines, a plura ity of cord circuits for interconnecting said lines including answering and calling plugs, an op.- erators telephone common to said cord circuits, plug seat switches for the answering and calling plugs, connections extending from said operators tele hone to said plug seat switches whereby w on any one o the answering plugs are removed from their seats the corresponding switch is operated to connect the operators telephone to this cord, the calling plug switches of said cords being operatedupon removal of the calling plug from the seat to again disconnect the operators telephone from the cord.

Si ned by us at Chica 0, county of Cook and tate of Illinois in t e presence of two witnesses.

RICHARD I. UTTER. HERMAN P. SCHMIDT. Witnesses:

G. E. MUELLER, B. OBRIEN. 

